Aaron Boes Profile picture
Neurologist & Neuroscientist: Lesion Mapping | Lesion Network Mapping | Brain Stimulation
Mar 22 16 tweets 5 min read
Why is the insula the most interesting region in the brain?

Here are 6 things worth knowing. This is topic #3 for our lab's Friday 'Ode to Neuroanatomy' series. Image Insula is Latin for island, which connotes detachment & isolation. It was a botched naming job in some respects, as the insula is an exceedingly well connected anatomical hub.
Mar 15 8 tweets 3 min read
Damage to this major occipitotemporal white matter tract can be associated with all except:

A) Inability to recognize faces
B) Inability to read
C) Monotone, emotionally flat speech
D) Lack of emotion to visual objects, including loved ones Image C. That is the inferior longitudinal fasciculus (ILF), a key tract for the 'what' ventral visual pathway.
Critical for recognizing visual objects and relating them to conceptual knowledge. Image
Mar 8 4 tweets 2 min read
A white matter lesion causes difficulty coming up with the names of items & frequent semantic errors. The responsible structure (red) is most likely…

A. Arcuate fasciculus
B. Inferior longitudinal fasc.
C. Inferior fronto-occipital fasc.
D. Superior longitudinal fasc. Image C. IFOF.

There is a narrow bottleneck of IFOF between ventral putamen and insula, such that a small lesion can disrupt a major anterior-posterior ventral white matter tract. IFOF is critical for semantic cognition, linking words & objects to conceptual knowledge. Image
May 5, 2023 12 tweets 5 min read
We see some strange and sometimes paradoxical effects of lesions to the default mode network.

A thread of some of the curious observations…. Image DMN is located as far away from primary motor and sensory cortices as possible –anatomically buffered from external reality and perfectly positioned to support stimulus-independent thought… simulating situations, replaying events, planning, ruminating.
pnas.org/doi/10.1073/pn… Image
Mar 15, 2023 10 tweets 4 min read
Is the wakefulness-promoting, consciousness-enabling influence of the brainstem left-lateralized in humans? Seems unlikely, right? In 2016 we did a lesion study of coma and our results suggested a left lateralization to a dorsolateral pontine tegmentum arousal-promoting region.

This was a small enough sample I think we all assumed the apparent laterality could have been by chance.
Oct 4, 2022 12 tweets 3 min read
@NickTrapp13 and our team evaluated depression symptoms in 526 people with focal brain lesions.

The 5 most important things we learned… 🧵 Image 1) Increased depression was seen after lesions of the insula –right insula was strongest association of anywhere in the brain.
Sep 4, 2022 11 tweets 4 min read
35 patients with precuneus lesions evaluated to date… here’s what we’re learning so far. 🧵 For context, part of the motivation for this line of research was to evaluate long-standing speculation that the precuneus has an important role in consciousness.

Is it warranted?
Jul 31, 2022 4 tweets 2 min read
This is an amazing story – Krista and Tatiana Hogan are conjoined twin sisters with distinct personalities and *mostly* separate brains that are linked by a ‘thalamic bridge.’ They can use it as a portal to access the other’s sensations and feelings. 👇 Tatiana doesn’t like ketchup and gets annoyed when Krista eats it because she will taste it too.

They can access visual information from the other's eyes and move the other’s limbs. Some modalities are apparently easier to access than others, with vision being more difficult.
May 24, 2022 4 tweets 2 min read
The individual with this precuneus lesion experienced a dramatic change in how he perceived the passage of time after surgery of a glioma.

Minutes felt like hours… each time he would check his watch he’d be surprised how little time had passed. 👇 Image A second person with a very similar lesion reported the same. There was a disorientation to time accompanied by a feeling like “time did not run.” It was even difficult to conceptualize what time was. Image